test: mark child-process-exec-kill-throws flaky

PR-URL: #12054
Ref: #12053
Ref: #11038
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Santiago Gimeno <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Richard Lau <[email protected]>

Author: gibfahn

test/parallel/parallel.status

@@ -7,6 +7,9 @@ prefix parallel
 [true] # This section applies to all platforms
 
 [$system==win32]
+# See https://github.com/nodejs/node/issues/12053, this test may be exposing a
+# genuine bug with kill() on Windows.
+test-child-process-exec-kill-throws : PASS,FLAKY
 
 [$system==linux]